<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
	</body>
</html>
<script type="text/javascript">
	function formate(date){
		// 设置默认值
		date = date || new Date();
		var y = date.getFullYear();
		console.log(y);
	}
	
	formate();
	
	const add = ({a=60,b=80}) =>{
		// 执行了解构let{a,b} = {a:200,b:300};
		return a+b;
	}
	
	var res = add({a:200,b:300});
	console.log(res);
	
	var res2 = add({});
	console.log(res2);
	
</script>
